SPI without CS

[rsoli.1]

I am using TLC5941 Led driver and it communicates with Nucleo-U575ZI-Q

and SPI on TLC using three wires only clock, MOSI and MISO and there is no CS

so I have an issue with connection so my question is:

Is there a way to make SPI on stm32 without CS?

[Foued_KH]

Hello @rsoli.1​ ,

CS -> Slave Select: Generated by the master to control which slave to talk to. It’s usually an active-low signal.

If a single slave is being addressed, you can tie the CS pin of this slave device to logic low without the need to control this line by the master.

So, you can communicate with SPI without CS .

Foued

[rsoli.1]

Hello

first thanks for fast reply but I want more information about "If a single slave is being addressed, you can tie the CS pin of this slave device to logic low without the need to control this line by the master."

how I could do it on Device configuration Tool?

[S.Ma]

Actually, reading the TI chip spec, it seems to me that XLAT is the renamed NSS signal.

This is the needed third signal to latch the pushed serial bit stream. The data lenght must match the number of daisy chained devices, then XLAT to store in each device the dimming values for each LED.

Anyway, all you need is just a GPIO, not necessarily NSS. It will be toggled by SW once the serialized buffer is pushed entirely out of the STM32.

[Pavel A.]

> Is there a way to make SPI on stm32 without CS?

Yes. Select the "Hardware NSS signal" as "disable" in the Device configuration Tool (aka Cube).

Then the SPI peripheral will not use any pin for CS (NSS).

[rsoli.1]

thanks for reply but I try to use code example of SPI but it is not worked I don't know what is the problem

and also I set the configuration as you say but there an problem the leds not worked anymore